What might account for a soldier experiencing syncope after standing at attention for a long period of time?
Increased respiratory rate.
Vasoconstriction.
Increased heart rate.
Venous pooling.
The Correct Answer is D
Choice D rationale
Venous pooling, particularly in the lower extremities, commonly occurs when standing still for prolonged periods due to the effects of gravity and reduced skeletal muscle pump activity. This pooling decreases venous return to the heart, leading to reduced cardiac output and consequently a drop in cerebral blood flow, which can result in syncope (fainting).
Choice A rationale
Increased respiratory rate (hyperventilation) typically leads to a decrease in carbon dioxide levels, causing respiratory alkalosis. While severe hyperventilation can lead to cerebral vasoconstriction and lightheadedness, it is not the primary physiological mechanism for syncope after prolonged standing.
Choice B rationale
Vasoconstriction, particularly systemic arteriolar vasoconstriction, would generally help maintain blood pressure by increasing total peripheral resistance, counteracting a drop in blood pressure. Therefore, it would typically prevent rather than cause syncope in this scenario, unless it was a compensatory, insufficient response.
Choice C rationale
An increased heart rate is a compensatory mechanism to maintain cardiac output when venous return or stroke volume is reduced, such as during orthostatic stress. While the heart rate does increase, it is often insufficient to prevent the fall in blood pressure that leads to syncope if venous pooling is severe.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
Choice A rationale
Adenoid tonsils, also known as pharyngeal tonsils, are located in the nasopharynx. While they can become enlarged and necessitate removal, they are not typically referred to as the "largest" and their removal is termed adenoidectomy, not tonsillectomy in general.
Choice B rationale
Lingual tonsils are located at the base of the tongue. They are much smaller than palatine tonsils and their removal is less common compared to palatine tonsillectomy. Their anatomical position differs significantly from the most commonly removed tonsils.
Choice C rationale
Palatine tonsils are situated on either side of the oropharynx, between the palatoglossal and palatopharyngeal arches. They are the largest of the tonsils and, due to their size and propensity for recurrent infections, historically were the most common tonsils removed in tonsillectomy procedures.
Choice D rationale
Pharyngeal tonsils, also known as adenoids, are located in the nasopharynx. They are distinct from the palatine tonsils and, while important lymphoid tissues, are not generally considered the largest or the primary target of a "tonsillectomy" in the historical context.
Correct Answer is B
Explanation
Choice A rationale
Antidiuretic hormone (ADH), also known as vasopressin, is synthesized in the hypothalamus and subsequently released from the posterior pituitary gland. Its primary function involves regulating water balance by increasing water reabsorption in the renal collecting ducts, thereby concentrating urine and preventing dehydration.
Choice B rationale
Luteinizing hormone (LH) is a gonadotropic hormone produced and secreted by the anterior pituitary gland. In females, it triggers ovulation and corpus luteum formation, while in males, it stimulates testosterone production by the Leydig cells. It is not synthesized in the hypothalamus.
Choice C rationale
Thyrotropin-releasing hormone (TRH) is a hypothalamic hormone that stimulates the anterior pituitary to release thyroid-stimulating hormone (TSH) and prolactin. This tripeptide hormone plays a crucial role in regulating thyroid function and lactation through its signaling pathways.
Choice D rationale
Somatostatin, also known as growth hormone-inhibiting hormone (GHIH), is a peptide hormone produced in the hypothalamus. It inhibits the release of growth hormone (GH) and thyroid-stimulating hormone (TSH) from the anterior pituitary, playing a vital role in neuroendocrine regulation and metabolism.
Choice E rationale
Prolactin-inhibiting hormone (PIH), primarily dopamine, is synthesized in the hypothalamus. It continuously inhibits the secretion of prolactin from the anterior pituitary gland, thus regulating lactation. A decrease in PIH allows for increased prolactin release, promoting milk synthesis.
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